The invention relates to compositions having enhanced vibration dampening properties and methods to improve the vibration dampening properties of compositions.
The invention also relates to articles formed out of the compositions.
One relatively recent focus in the automobile industry has been the control and, preferably, the elimination of noise occurring as the result of the vibration of automobile body panels. To this end, important reductions in automobile noise levels have been achieved by the vibration damping of automobile body panels such as instrument panels, floor panels, door panels, roof panels, and fender panels, among others. To effectuate vibration damping, compositions containing fillers dispersed in binders have been widely used to coat metallic surfaces of automobile body panels to provide the desired vibration damping and/or sound deadening. For example, sheet materials of heat softenable compositions including asphalt, fillers and natural and/or synthetic elastomers have been used for sound deadening.
With the wide acceptance of plastic resins in the automobile industry for weight reduction, part consolidation, and recycle capability combined with the ever increasing demand for the increased noise management, there is a continuing need for new methods and compositions for noise control.
The needs discussed above have been generally satisfied by the discovery of a composition comprising:
(a) a polymer system selected from the group consisting of immiscible polymer blends, miscible polymer blends, copolymers, thermoplastic polymers and thermosetting polymers, and
(b) a block copolymer comprising:
(i) at least one block derived from aromatic vinyl units and
(ii) at least one block having a glass transition temperature of at least about 10xc2x0 C. derived from at least isoprene and vinyl aromatic monomers, optionally with butadiene.
Component (b)(i) is preferably derived from at least one of styrene and xcex1-methylstyrene and component (b)(ii) is preferably derived from at least one of styrene and xcex1-methylstyrene combined with isoprene. The polymer system is preferably comprises at least one of polyphenylene ether resin, polyamide resin, polystyrene resin, poly(acrylonitrile-butadiene-styrene) resins, polycarbonate resin, and polyester resin.
In a preferred embodiment, the invention affords a method for enhancing the vibration dampening characteristics of composition, wherein the method comprises:
(a) a polymer system selected from the group consisting of immiscible polymer blends, miscible polymer blends, copolymers, thermoplastic polymers and thermosetting polymers, and
(b) a block copolymer comprising:
(i) at least one block derived from aromatic vinyl units and
(ii) at least on ck having a glass transition temperature of at least about 10xc2x0 C. derived from at least isoprene and vinyl aromatic monomers, optionally with butadiene.
Articles made from the improved compositions as well as articles that utilize the method for enhancing the vibration dampening characteristics are included within the scope of the invention. The description that follows provides further details regarding various embodiments of the invention.